Steve Wrote:
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> I performed a contrast between two groups using
> 3dmema and included a covariate. I am actually
> interested in the regions covarying with my
> behavioral measure (the covariate), rather than
> the contrasts with covariate removed. I see that
> there are actually two covariate subbricks pairs
> (each with a beta and t-stat), the second pair has
> an "X" at the end. My guess is that the first
> subbrick pair [6..7] represents the regions of
> covariance when collapsing across groups, while
> the second pair [8..9] with the "X" represents the
> between group differences with respect to the
> covariate (i.e., between group differences for the
> regression slope of the covariate) because I
> specified that I wanted two separate slopes for
> each group. Is this correct? Please let me know if
> I need to be more clear or if more information is
> needed. Thanks in advance.

Hi Steve, I assume that you used option "-covariates_model slope=different". If so, the subbrick pair [6..7] is for the covariate effect of the first group, and second pair [8..9] with the "X" is for the difference of group2 - group1 in covariate effect (the amount of covariate effect in group2 more than group1).

Gang



Edited 1 time(s). Last edit at 06/01/2012 10:16PM by Gang.